//--------------------------------------------------------------------------
//	Copyright (c) 1998-2004, Drew Davidson and Luke Blanshard
//  All rights reserved.
//
//	Redistribution and use in source and binary forms, with or without
//  modification, are permitted provided that the following conditions are
//  met:
//
//	Redistributions of source code must retain the above copyright notice,
//  this list of conditions and the following disclaimer.
//	Redistributions in binary form must reproduce the above copyright
//  notice, this list of conditions and the following disclaimer in the
//  documentation and/or other materials provided with the distribution.
//	Neither the name of the Drew Davidson nor the names of its contributors
//  may be used to endorse or promote products derived from this software
//  without specific prior written permission.
//
//	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
//  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
//  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
//  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
//  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
//  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
//  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
//  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
//  AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
//  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
//  THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
//  DAMAGE.
//--------------------------------------------------------------------------
package com.feilong.lib.ognl;

import java.lang.reflect.Method;

/**
 * Superclass for OGNL exceptions, incorporating an optional encapsulated exception.
 *
 * @author Luke Blanshard (blanshlu@netscape.net)
 * @author Drew Davidson (drew@ognl.org)
 */
public class OgnlException extends Exception{
    // cache initCause method - if available..to be used during throwable constructor
    // to properly setup superclass.

    /**
     * 
     */
    private static final long serialVersionUID = 7126968273583084747L;

    static Method             _initCause;
    static{
        try{
            _initCause = OgnlException.class.getMethod("initCause", new Class[] { Throwable.class });
        }catch (NoSuchMethodException e){ /** ignore */
        }
    }

    /**
     * The root evaluation of the expression when the exception was thrown
     */
    private Evaluation      _evaluation;

    /**
     * Why this exception was thrown.
     * 
     * @serial
     */
    private final Throwable _reason;

    /**
     * Constructs an OgnlException with the given message but no encapsulated exception.
     * 
     * @param msg
     *            the exception's detail message
     */
    public OgnlException(String msg){
        this(msg, null);
    }

    /**
     * Constructs an OgnlException with the given message and encapsulated exception.
     * 
     * @param msg
     *            the exception's detail message
     * @param reason
     *            the encapsulated exception
     */
    public OgnlException(String msg, Throwable reason){
        super(msg);
        this._reason = reason;

        if (_initCause != null){
            try{
                _initCause.invoke(this, new Object[] { reason });
            }catch (Exception t){ /** ignore */
            }
        }
    }

    /**
     * Sets the Evaluation that was current when this exception was thrown.
     *
     * @param value
     *            The {@link Evaluation}.
     */
    public void setEvaluation(Evaluation value){
        _evaluation = value;
    }

    /**
     * Returns a string representation of this exception.
     * 
     * @return a string representation of this exception
     */
    @Override
    public String toString(){
        if (_reason == null){
            return super.toString();
        }

        return super.toString() + " [" + _reason + "]";
    }

    /**
     * Prints the stack trace for this (and possibly the encapsulated) exception on
     * System.err.
     */
    @Override
    public void printStackTrace(){
        printStackTrace(System.err);
    }

    /**
     * Prints the stack trace for this (and possibly the encapsulated) exception on the
     * given print stream.
     */
    @Override
    public void printStackTrace(java.io.PrintStream s){
        synchronized (s){
            super.printStackTrace(s);
            if (_reason != null){
                s.println("/-- Encapsulated exception ------------\\");
                _reason.printStackTrace(s);
                s.println("\\--------------------------------------/");
            }
        }
    }

    /**
     * Prints the stack trace for this (and possibly the encapsulated) exception on the
     * given print writer.
     */
    @Override
    public void printStackTrace(java.io.PrintWriter s){
        synchronized (s){
            super.printStackTrace(s);
            if (_reason != null){
                s.println("/-- Encapsulated exception ------------\\");
                _reason.printStackTrace(s);
                s.println("\\--------------------------------------/");
            }
        }
    }
}
